1. Field of the Invention
The present invention relates to a rod integrator and the method of manufacturing the same.
2. Related Background Art
In a liquid crystal projector or the like, the beam emitted from a light source is guided into a liquid crystal panel as illumination light. Then, the beam incident into a liquid crystal panel is modulated on the basis of the image information, and the modulated beam is outputted from the liquid crystal panel. The beam from the liquid crystal panel is projected onto a screen. In such a liquid crystal projector, if the light on the surface of the liquid crystal panel is not uniform, illuminance unevenness occurs in the image on the screen. Hence a means of obtaining the uniformity of the light on the liquid crystal panel is conventionally used. A rod integrator is known as the means.
As the rod integrator, a rod prism formed from glass (Japanese Patent Laid-open No. 11-326727) or a tube-shape body having inner mirror surfaces is well known. The rod prism integrator is disclosed in Japanese Patent Laid-open No. 11-326727. The beam which is emitted from a light source is introduced directly into the first end surface or incidence end surface of the rod integrator or through the reflection on the reflector, and is guided to the second end surface or emission end surface of the rod integrator opposing the incidence end surface, which being reflected by the side surfaces of the rod integrator. As a result, the light on the emission end surface can be made substantially uniform. The emission end surface of the rod integrator and the liquid crystal panel are placed in a conjugate relationship, so that the light on the liquid crystal panel turns into uniform. The arrangement and the operations of the tube-shape integrator in a liquid crystal projector are similar to the rod prism integrator.
However, in the rod prism integrator as described above, there arise the following problems. That is, scratches or dust on the emission end surface of the rod prism integrator are imaged on the surface of the liquid crystal panel.
In the above-mentioned tube-shape integrator, there is no problem on the basis of the scratches or dust, because there is no end surface at the end portion of the tube-shape integrator from which the beam is outputted. However, there arise the problems that the quantity of light from the light source is greatly decreased through the tube-shape integrator while being reflected by inner mirror surfaces, because of the difficulty to obtain the mirror surface with 100% reflectivity.
An object of the present invention is to provide a rod integrator and a method of manufacturing of the same, which can resolve the above-described problems.